There is a stapler of a cartridge type for binding a staple by mounting a cartridge contained with a number of unformed straight staples to a magazine portion of an electric stapler, successively supplying the unformed staple at an inside of the cartridge to a strike out path formed at a front end of a path of supplying the staple of the cartridge, forming the unformed staple in a C-shape by a forming plate immediately before the strike out path and supplying the formed staple to an inside of the strike out path in which a driver plate is moved to slide, striking out the formed staple from the strike out path by the driver plate, and penetrating the staple leg through binding sheets arranged at a lower face of the cartridge.
A front end portion of the cartridge contained with the number of staples is formed with the strike out path for striking out a front one of the staples to the binding sheet, and the strike out path is formed between a front end face of the cartridge and a face plate attached to a front end portion of the cartridge. The driver plate driven reciprocally by a motor provided on a main body side of the electric stapler strikes out the staple arranged at the inside of the strike out path by advancing to inside of the strike out path formed at the front end portion of the cartridge and folds to bend a front end of a staple leg penetrated through the binding sheets arranged on a lower face side of the cartridge by a clincher mechanism.
According to an electric stapler according to the related art of the application, there is formed an anvil arranged at a lower face of the unformed staple immediately before the strike out path, the unformed staple is formed into a C-shape by the anvil and the forming plate, and the staple formed in the C-shape is supplied to the inside of the strike out path by a pusher arranged on a lower side of the anvil. The pusher is moved back when the unformed staple is formed into the C-shape by the forming plate, engaged with the rear face side of the staple formed in the C-shape and presses the formed staple to a front side by a spring urge force to supply to an inside of a groove formed at a back face of a face plate forming the strike out path. Further, the pusher presses the staple leg portion from the rear face side to guide the struck-out staple leg portion when the staple at the inside of the strike out path is struck out by the driver plate.
The pusher is moved back by bringing the staple leg in the midst of being formed by starting to form the unformed staple by the forming plate into contact with the pusher, and presses the staple in a direction of the strike out path by being engaged with the rear face side of the staple formed in the C-shape. When the pusher is moved back, a support force for pushing the staple arranged at the inside of the strike out path and in the midst of being back from the rear face side is lost to bring about a case in which the staple is not guided sufficiently. When a length of the staple leg formed in the C-shape is long, also a thickness of the binding sheets is large and therefore, a large penetration resistance is produced during a time period after landing a front end of the staple leg struck out by pressing a crown portion thereof by the driver plate on a surface of the binding sheets, until penetrating the front end of the staple leg through the binding sheets, a distance between the driver plate and the front end of the staple leg is large and therefore, when the support force from the rear side is lost as described above, jamming is liable to be brought about by buckling the staple leg.
Hence, WO2004/048054 discloses a staple in which a pusher is formed with a long guide piece continuous in a staple striking out direction by way of an inclined face to be formed to project integrally to a side of the face plate to advance to between two legs of the staple at the inside of the strike out path, and the staple leg is guided by the guide piece by forming the inclined face at a position of being engaged with the staple when a front end of the staple leg struck out by the driver plate is landed on the binding sheets.
However, also according to the electric stapler, the pusher is moved back simultaneously with folding to bend the straight staple into the C-shape by the forming plate on the rear face side of the driver plate and therefore, a front one of the formed staple is liable to be unstable by losing the support invariably. Therefore, there is a case in which the staple is buckled before finishing to penetrate the binding sheets in the midst of being struck out. There is brought about an unstable struck state to cause to bring about a failure in striking such as jamming or the like.